Willem Jiang 519200728a

fix(middleware): offload memory injection off event loop to prevent tiktoken blocking (#3402) (#3411) ...

* fix(middleware): offload memory injection off event loop to prevent tiktoken blocking (#3402)

  DynamicContextMiddleware.abefore_agent() called _inject() synchronously
  on the asyncio event loop.  The first time memory is injected (second
  request), _inject() → format_memory_for_injection() → _count_tokens()
  → tiktoken.get_encoding("cl100k_base") needs to download the BPE data
  from openaipublic.blob.core.windows.net.  In network-restricted
  environments this download blocks until the OS TCP timeout (~26 min),
  starving ALL concurrent handlers including /api/v1/auth/me.

  Fix:
  - abefore_agent now uses asyncio.to_thread(self._inject, state) so
    file I/O and tiktoken never block the event loop.
  - Extract _get_tiktoken_encoding() with a module-level cache so
    tiktoken.get_encoding() is called at most once per encoding name.
  - Add warm_tiktoken_cache() startup helper; gateway lifespan pre-warms
    the cache via asyncio.to_thread so the first request never triggers a
    cold download.
  - _count_tokens falls back to len(text) // 4 on any encoding failure.

  Tests:
  - tests/test_tiktoken_cache_and_count_tokens.py (12 tests): cache
    hit/miss, fallback paths, warm-up helper.
  - tests/blocking_io/test_dynamic_context_middleware.py (2 tests):
    Blockbuster gate verifies abefore_agent does not block the event
    loop; async/sync parity check.

  Fixes #3402

* Apply suggestions from code review

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

* fix the lint error

* fix(memory): use future annotations to avoid NameError when tiktoken is absent

Add `from __future__ import annotations` to prompt.py so that
tiktoken.Encoding type hints are never evaluated at runtime.  Without
this, environments where tiktoken is not installed could raise NameError
on the module-level cache and function return annotations.

Addresses Copilot review comment on PR #3411.

* fix(middleware): bound abefore_agent injection with timeout to prevent hung requests

Wrap the asyncio.to_thread(self._inject) offload in asyncio.wait_for()
with a 5-second cap.  If the startup warm-up failed silently (e.g.
network blip during deploy), a cold tiktoken BPE download on the first
request can block until the OS TCP timeout (~26 min).  The bounded
timeout ensures the request degrades gracefully (no memory/date context
for that turn) rather than hanging.

Adds test_abefore_agent_returns_none_on_timeout to the blocking-IO
regression anchors.

Addresses review feedback from xg-gh-25 on PR #3411.

---------

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

2026-06-08 12:21:55 +08:00

..

channels

fix(mcp): add auth interceptor with channel user_id and keep header propagation to mcp tools (#3294)

2026-06-03 15:48:19 +08:00

gateway

fix(middleware): offload memory injection off event loop to prevent tiktoken blocking (#3402) (#3411)

2026-06-08 12:21:55 +08:00

__init__.py

refactor: split backend into harness (deerflow.*) and app (app.*) (#1131)

2026-03-14 22:55:52 +08:00